In recent years, plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs) are commonly used. In such vehicles, a high voltage battery, a low voltage battery, and an in-vehicle charging apparatus are mounted. The high voltage battery is a power source for driving a motor and the like of the vehicle, and the low voltage battery is a power source for operating an engine control unit (ECU) of the in-vehicle charging apparatus. The in-vehicle charging apparatus is connected with the external power source (hereinafter referred to as “external power source”), and controls charging of the high voltage battery and the low voltage battery from the external power source.
In such a configuration, in a case where the remaining capacity of the low voltage battery is insufficient (in a case of battery exhaustion), the operation of the ECU is stopped, and as a result charging of the batteries cannot be performed. In view of this, for example, PTL 1 discloses a technique in which charging from an external power source to an ECU is performed with use of a path other than a path connected to a high voltage battery and a path connected to a low voltage battery. In this manner, with the technique disclosed in PTL 1, even when the remaining capacity of the low voltage battery is insufficient, the ECU can operate, and therefore charging of batteries can be performed.